| Northeastern Illinois
General Information |
Groundwater Quality As a general rule, the water in the deep bedrock aquifers tends to be more mineralized than shallow aquifers, but it varies from location to location. The potential for contamination by vertical migration of chemicals from the land surface is very low; however, other contaminant pathways, such as abandoned wells, can pose a threat to the groundwater quality in the deep bedrock. The Cambrian-Ordovician is also known to contain high concentrations of naturally occurring barium and radium.
Lake Michigan Diversion U.S. Supreme Court decrees limit Illinois to diverting an average of 3,200 cubic feet per second (cfs) from Lake Michigan. Illinois exceeded this limit during 11 of the 15 years from 1981 through 1995; the State diversion averaged 3,197 cfs during 1995. Essentially, Lake Michigan water is already fully allocated. Increasing Demands The Northeastern Illinois Planning Commission projects the population of the six northeastern counties to grow by 25 percent by 2020 and that of the outer collar counties to increase by 70 to 100 percent by 2020. Deregulation of the power industry, low natural gas prices, and the ever-increasing need for electrical power have combined in an explosion of proposals for peaking power plants in northeastern Illinois, placing yet additional demands for water on already scarce resources. Science for Water Resources Management As a result of aggressive resource evaluation and management, Illinois has reduced Cambrian-Ordovician pumpage in the Chicago region to near the practical sustained yield of the aquifer. However, this aquifer system and Lake Michigan are now at or near their sustainable or legally mandated limits and cannot be relied upon as significant sources of additional water for the region. The most viable water source alternatives for northeastern Illinois are the shallow aquifers and the Fox, Des Plaines, and Kankakee Rivers. Shallow groundwater resources and surface streams are hydraulically connected and withdrawal of water from the shallower systems is likely to have an effect on stream flow and wetlands. Consequently, conjunctive use scenarios must be examined through the collection of field data and computer modeling. In addition, shallow aquifers are vulnerable to surface-derived contaminants, and the intensity of urban development in the region has contributed to shallow groundwater quality degradation (e.g., Lake Calumet). The Water Resources Task Force of the Northeastern Illinois Planning Commission also recognized this need to quantify surface water and groundwater resource use, capacity, and quality in northeastern Illinois in recommending additional resources be provided to the Water Survey to support research and data collection. |
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